The present invention relates to a door frame and a method of its assembly. More particularly, it relates to square butt hollow door frames. Numerous arrangements of this general type are shown in the prior art U.S. Pat. Nos. 3,004,641, 3,343,318, 3,827,485, 4,077,160, 4,327,535, 4,387,545, 4,546,585 and 4,606,170. None of the prior art discloses the features of the present invention.